Pr0.7(Sr1-xCax)0.3MnO3多晶体系中的小极化子性质

采用基于柠檬酸体系的溶胶-凝胶法制备了Pr_0.7（Sr_1-xCa_x）_0.3MnO₃系列的多晶块材, 同时还用脉冲激光沉积技术（PLD）在SrTiO₃（100）衬底上外延生长了同一系列的薄膜, 系统研究了它们的晶格结构和电输运行为. 多晶和薄膜样品都具有正交晶格结构, 电输运行为在居里温度T_Ｃ以上的高温顺磁相都很好 关键词： 0.7（Sr_1-xCa_x）_0.3MnO₃')" href="#">Pr_0.7（Sr_1-xCa_x）_0.3MnO₃ 绝热小极化子模型 双交换作用 Jahn-Teller晶格畸变

Small polaron property of polycrystalline Pr0.7(Sr1-xCax)0.3MnO3 series

We have synthesized polycrystalline bars of Pr_0.7（Sr_1-xCa_x）_0.3MnO₃（x=0，0.1，…，1）with a sol-gel method using citrate as an agent, and grown epitaxial thin films of Pr_0.7（Sr_1-xCa_x）_0.3MnO₃ on （100）-oriented substrates of SrTiO₃ （ STO ） by using pulsed laser deposition （ PLD ）. We systemically investigated their lattice structures and electronic transport property. Both polycrystalline and film samples have orthorhombic lattice structure, and their electronic transport behaviors nicely follow a adiabatic small polaron model in high temperature paramagnetic phase when T is larger than the Curie temperature T_C. All resistivity data have been fitted by the small polaron model. The fitted results of polycrystalline samples qualitatively agree with that of corresponding film samples. With increasing contents of Ca, polaron hopping energy E_hop increases monotoniccaly, and ρ₀ first decreases, then increases. The above results indicate that electronic transport property of high quality polycrystalline samples is less influenced by lattice defects and grain boundaries which are abundant in low quality samples, such that intrinsic small polaron transport behavior can appear in the former.